4482-22-8Relevant academic research and scientific papers
Substrate dependent synergetic and antagonistic interaction of ammonium halide and polyoxometalate catalysts in the synthesis of cyclic carbonates from oleochemical epoxides and CO2
Langanke, Jens,Greiner, Lasse,Leitner, Walter
supporting information, p. 1173 - 1182 (2013/06/27)
Organic halides and polyoxometalates (POMs) were studied as catalyst systems for the insertion of carbon dioxide into epoxides originating from plant oils as biogenic feedstock. In the formation of methyl oleate carbonate, synergistic rate acceleration and increased cis-selectivity were observed using ammonium halide and transition metal substituted silicotungstate POMs catalysts in a combined system. Mechanistic insight into the cooperative action was gained by kinetic measurements and analysis of the stereochemical outcome of the reaction. For poly-epoxidised oleochemicals as substrates, the simple ammonium halide catalyst gave better performance as side reactions were encountered with the POM-containing system.
Epoxidation, hydroxylation and aromatization is catalyzed by a peroxygenase from Solanum lycopersicum
Fuchs, Christopher,Schwab, Wilfried
, p. 52 - 60 (2013/10/22)
Plant peroxygenase (PXG) oxidizes unsaturated fatty acids by transferring an oxygen atom of a hydroperoxide to the double bond, thereby providing epoxides. In this work we investigated the potential of a PXG from tomato (Solanum lycopersicum, SlPXG) to catalyze the oxidation of a variety of natural products. A SlPXG gene was cloned from tomato, heterologously expressed in yeast and the membrane bound recombinant SlPXG protein was used as enzyme source. Unsaturated fatty acids, fatty acid derivatives, and terpenes were epoxidized by SlPXG in the presence of various hydroperoxides exclusively at their cis-double bonds. Terpenes with p-menthene skeleton were transformed in different ways depending on their molecular structures. R-(+)- and S-(-)-limonene were converted to R-(+)-limonene-trans-1,2-epoxide (97%) and cis-S-(-)-limonene-1,2- epoxide (88%), respectively whereas α-terpinenewas hydroxylated to cis-1,4-dihydroxy-p-menth-2-ene and γ-terpinene was aromatized to p-cymene. In the last reaction the hydroperoxide served as hydrogen acceptor rather than an oxygen donor. PXG appears to be a versatile biocatalyst able to perform different kinds of oxidation reactions. As no cofactors like NAD(P)H are required and H2O2is an environmentally friendly oxidant, PXG enables new applications for the synthesis of fine chemicals from renewable resources.
A three-step-one-pot chemo-enzymatic synthesis of epoxyalkanolacylates
Klaas, M. Ruesch,Warwel
, p. 251 - 260 (2007/10/03)
Using the ability of Novozym 435 to catalyze both the perhydrolysis and the interesterification of esters, unsaturated primary alcohols are converted with an ester and hydrogen peroxide to give esters of epoxidized alcohols directly in a convenient three-step-one-pot synthesis with yields of 66-89%.
An Inexpensive Air-Stable Titanium-Based System for the Conversion of Esters to Primary Alcohols
Reding, Matthew T.,Buchwald, Stephen L.
, p. 7884 - 7890 (2007/10/03)
Polymethylhydroxiloxane, when combined with titanium(IV) isopropoxide, provides a convenient system for the conversion of esters to the corresponding primary alcohols in the presence of a wide range of functional groups.Reactions are carried out as mixtures of the neat reaction components; workup with aqueous alkaline THF affords primary alcohols in good to excellent yields.The system tolerates primary alkyl bromides and iodides, olefins, epoxides, and alkynes.Steric differentiation of methyl and tert-butyl esters is also possible.The results observed in the parent and related reactions argue against pathways involving Lewis-acid catalysis and anionic hydridosilicate-mediated reductions, and instead support a neutral titanium hydride complex or strongly associated titanium/silane complex as the active reducing agent.
An Air-Stable Catalyst System for the Conversion of Esters to Alcohols
Berk, Scott C.,Buchwald, Stephen L.
, p. 3751 - 3753 (2007/10/02)
The combination of 5 mol percent of Ti(O-i-Pr)4 with 2.5-3.0 equiv (EtO)3SiH cleanly hydrosilylates esters to silyl ethers at 40-55 deg C, which can be converted to the corresponding primary alcohols via aqueous alkaline hydrolysis in excellent overall yield.The reaction can be carried out in the air, without solvent, and displays a high level of functional group compatibility.
